Student or Learner
That's what it means here. But it's interesting to note that in the IT world (may be in AmE more generally) `show-stopper' is often used with the opposite sense. I worked with software engineers who operated a scale of bug, ranging from the least important ("P5") to the most ("P1). The worst bugs, bad enough to prevent a product from shipping, were "P1-show-stopper". They stopped the show all right, but by being bad.
from dictionary :
bug = a mistake or problem in a computer program:
but, what is `scale of bug'?
Also, does the word `but' here mean `except'?
and also, what is `all right' in this context?
Please explain the bold highlighted ones.
The word 'scale' basically indicates 'size' or 'extent' in the context. The word scale would be similar used this way:
"On a scale of 1 to 5, how bad is the bug? Oh, it's very bad! It's a P1!"
Rewording:They stopped the show all right, but by being bad.
Those bugs did indeed "stop the show" -- not because they were very good, however. (Instead it was because they were so bad.)